PROJECT SUMMARY This K01 application is designed to provide Jessica King, PhD, with the mentored training necessary to transition into an independent tobacco regulatory science researcher. Dr. King will be mentored by a team of renowned tobacco control and tobacco regulatory scientists and will complete mentored training, coursework, and professional development in the areas of advanced statistical analyses, policy impact analyses, and health disparities. This additional career development and mentorship will directly contribute to completing the proposed research strategy, which examines the impact of cigar pack quantity on tobacco use behaviors. Cigar use is the third most commonly used tobacco product among adults, and second most commonly used product among youth, with use increasing among low income, minority, and young adult populations. Given the significant health effects attributable to cigar use, this represents a critical health disparity. Low cost is often cited as a reason for increased use among these populations, in part due to low taxes and varying pack quantities. Research on cigarettes has shown minimum pack quantity laws increase price and decrease use. As of 2016, the FDA has regulatory authority over cigars, allowing it to regulate the marketing, manufacturing, and distribution of cigar products, including mandating minimum pack quantities. However, cigar-specific data are needed to inform FDA's regulation. Thus, the goal of the proposed analyses are to advance understanding of the relationship between cigar pack quantity and tobacco use behaviors to inform regulation on minimum cigar pack quantity. Specifically, we aim to (1) assess whether cigar pack quantity is associated with between- and within-person changes in cigar use and whether there are differences by sociodemographic factors, (2-3) identify the impact of local minimum cigar pack quantity laws on cigar and other tobacco use and cigar sales and whether impacts differ across communities of varying demographics, and (4) characterize differences in the implementation and enforcement of minimum cigar pack quantity laws through qualitative interviews with key implementation personnel. In this mixed-methods approach, we will utilize national datasets, including the Population Assessment of Tobacco and Health Study, the Tobacco Use Supplement to the Current Population Survey, the Youth Risk Behavior Surveillance System, and Nielsen retail scanner data. Each aim will explicitly examine the impact among racial and ethnic minorities, low income populations, youth, and young adults, each vulnerable populations. This research will directly address the FDA Center for Tobacco Products Scientific Domains of behavior and impact analysis. The findings from this study may inform future FDA rulemaking on cigar pack quantity.